Allow glob-level configuration for lint rules

[atty-stripe]

Proposal

I would like support for selectively enabling lint rules at a per-directory (or glob) level.

We have a large codebase at Stripe that did not start with the strictest lint rules. What we would like to do is enable new lint rules in specific directories, so that new code written in those directories can be safer. Over time, we can migrate other directories to accept new lint rules.

This can either be implemented with an extension to .flowconfig, or perhaps allowing per-directory .flowconfig files that can inherit from parent directory .flowconfig files. I don't have strong opinions for a solution, but would love to see this problem solved.

Use case

See above.

[kevinbarabash]

It would be nice if there was a way to enable/disable on a per file basis too.

[jamesisaac]

For anyone not aware, you can get part of the way there with @flow strict annotations on files you want to be checked against a stricter set of rules (configurable in .flowconfig which lint rules those are):

https://flow.org/en/docs/strict/